Releasable detent mechanism



Nov. 10, 1953 c, B, LIVERS 2,658,410

RELEASABLE DETENT MECHANISM Original Filed Oct. 31, 1949 2 Sheets-Sheet I 26 65 3a 49 Zi 9 /Zf-ZZ 22 63 I N 37 L r o INVENTOR C. B. LIVERS ATTORNEY NOV. 10, 1953 g, B, LlVERs 2,658,410

RELEASABLE DETEINT MECHANISM Original Filed Oct. 51, 1949 2 Sheets-Sheet 2 4} 1 /22 6.? 50 j 4 lll'll lll|l 455! I 4/;

24 62 55 5f 32 3563 49 j if 37 I V I 4/ 3/ N924; i2 40 3/ i Q INVENTOR c. B. LIVERS ATTORNEY Patented Nov. 10, 1953 RELEASABLE DETENT vMECHANISM Carlos B. Livers, North Hollywood, Calif., assignor to Bendix Aviation Corporation, North Holly- I wood, Calif a corporation of Delaware Original application October 31, 1949, Serial No.

Divided and this application April 16, 1951, Serial N0. 221,271

, 1 Claim. 1

This invention relates to detent mechanisms for retaining two relatively slidable members in predetermined relative positions, and more particularly to detent mechanisms capable of being selectively disabled to permit the two members to move out of the said predetermined relative positions.

An object of the invention is to provide a simple and inexpensive detent mechanism which can be readily manipulated to vary its holdingpower between wide limits.

A more specific object is to provide a detent mechanism with controllable release which is particularly adapted for retaining a hydraulic valve in desired positions of operation.

Other more specific objects and features of the invention will appear from the description to follow:

Briefly, a detent mechanism in accordance with the invention comprises two relatively reciprocable telescoping members the outer of which contains an annular groove containing a garter spring, and the inner of which consists of two longitudinally separable cylindrical elements. The latter elements can be selectively separated ashort distance to define a groove engageable by the garter spring and to hold the two members in desired relative position, or the elements can be moved together into abutting condition to define a continuous cylindrical surface offering little resistance to movement past the garter spring.

This application is a division of application Serial No. 124,711, filed October 31, 1949, in the names of C. B. Livers and A. A. Meddock and titled Hydraulic Control Valve With Automatic Hold and Release, now Patent No. 2,594,664.

The invention will now be explained by describing in detail a valve incorporating it.

In the drawing:

Fig. 1 is a schematic diagram of a hydraulic system incorporating a valve containing a detent mechanism in accordance with the present invention;

Figs. 2, 3, 4 and are longitudinal sectional views through the valve, showing different stages of operation thereof; and

Fig. 6 is a longitudinal sectional view through the right end portion of the valve, showing still another stage in the operation thereof.

Referring to Fig. 1, the hydraulic system therein depicted comprises a motor cylinder l0 containing a piston Illa. connected to a piston rod I 0b which projects from the cylinder and is connected to any device to be operated by the motor. The cylinder lflihasfluid ports, at its opposite ends connected by fluid lines l2 and I3 respec tively to motor ports 21 and 28 in a control valve [4 which constitutes the present invention. The valve M has an actuating handle l5 and has a pair of ports 25 and 26, one of which, 25 is an inlet port and is connected by a line It to the output of a pump l1, and the other of which, 26, is an outlet port and is connected by a line l8 to a fluid supply reservoir IS. The intake of the pump H is connected by a line 2!!- to the reservoir l9.

Referring to Fig. 2, the valve I4 comprises a body member 22 having a bore23 cooperating with a movable member consisting of a piston 24 which functions to interconnect the ports in the body in a desired manner in different positions of the piston. The valve piston 24 extends out of the left end of the body 22, and is shown as having an annular groove 2411 which is engaged by a pin l5a on the lower end of the handle l5, for manual actuation of the piston by the handle. Fig. 2 shows the valve in neutral position in which the inlet port 25 is directly connected to the outlet port 26, so that fluid supplied to the inlet port 25 by the pump circulates freely through the valve and out of the outlet port 26,

without developing pressure. At the same time, lands 24b and 240 of the valve piston 24 block the motor ports 21 and 28, to prevent escape of fluid from either end of the motor cylinder Ill and thereby hold it in whatever position it has been operated into.

Now let it be assumed that the handle I5 is rocked to the left, as shown in Fig. 3. This moves a land 24d, on the valve piston 24 into blocking relation between the inlet and outlet ports 25 and 26 respectively, so that the pumped fluid is no longer freely bypassed. However, this movement of the valve piston carries the land 24c clear of the motor port 28, so that the latter is communicated through radial passages 3|, a longitudinal passage 32, and radial passages 33 in the piston 24, with the inlet port 25, permitting fluid to flow through the motor line 12 into the left end of the motor cylinder 10 and move the piston therein to the right. At the same time, fluid is exhausted from the right end of the motor cylinder [0 through the motor line [3 into the motor port 21 of the valve 24 and thence through the return port 26 back to the reservoir. During movement of the motor piston I, it is restricted only by the resistance of the load to Whichthe piston rod 10b is connected, and the pressure 'in the valve will be less than a prede termined' maximum.

The valve piston 24, after being moved into the open position shown in Fig. 3, is yieldably held open by a detent means, so that the operator does not have to hold the handle l while the motor piston Illa is going through its movement. This detent means will now be described.

Referring to Fig. 2, a spring-closed relief valve 34 normally closes the right end of the longitudinal passage 32 in the piston 24. This valve 34, asshown, is cylindrical in shape and is slideable in a bore 320:, in the valve piston, the bore 32a constituting an enlarged extension of the longitudinal passage 32.

The valve 34 projects to the right beyond the end of the bore 32a, and is connected by a transverse pin 35 to a sleeve 36 (shown most clearly in the large scale view of Fig. 6) that is slideable in the right end of the bore 23 in the valve body. The valve piston 24 has an integral sleeve 24c extending from the right end thereof, this sleeve being of smaller diameter and telescoping with the sleeve 35, which is attached to the relief valve 34 for movement therewith. Slots 31 are provided in the sleeve 242 through which the pins 35 extend so that the sleeve 36 and the relief valve 34 can move relative to the sleeve 24c. The relief valve 34 is normally held in closed position (as shown in Figs. 2 and 3) by a helical compressio spring 39 compressed between the right end of the valve 34 and a pin 40 which extends through the sleeve 24c and through a sleeve 4| that surrounds it, the sleeve 4| being of the same outer diameter as the sleeve 36.

As shown in Fig. 2, when the valv 34 is in normal, closed, position, the two sleeves 36 and 4| are slightly separated to define a gap or recess 45 therebetween. When the valve piston 24 is moved to the right, as shown in Fig. 3, the sleeves 36 and 45 move therewith as a unit, carrying the gap 45 into registration with an annular detent spring 48 positioned in an annular groove 49 in the body 22. The spring 48 thereupon snaps into the gap 45 and holds the valve piston in operative position against the restoring force of a centering spring 50.

The centering spring 50 consists of a helical compression spring compressed between a flange 52a on a collar 52 and a washer 53 that is slideable on the sleeve 4|, and that normally rests against the edge of an end closure cap 55 which is secured in a counter-bore in the right end of the body 22 by an annular, split retainer spring 55, The collar 52 has an inwardly extending flange 52b which slides on the sleeve 4|, and is limited in its sliding movement by an annular, split spring ring 51 mounted in an annular groove in the outer surface of the sleeve 4|. The centering spring 50 urges the valve piston toward neutral position whenever it is displaced therefrom in either direction. Thus, as shown in Fig. 3, the internal flange 52b on the collar 52 bears against the ring 5? on the sleeve 4| thereby urging the sleeve 4|, the sleeve 24c and the valve piston 24 to the left. When the piston is displaced out of neutral position to the left, as shown in Fig. 5, the washer 53 is carried by a retaining ring 59 on the sleeve 4| to the left thereby compressing th centering spring 53, the left end of the collar 52 at that time bottoming against the shoulder 65 in the valve body.

The annular helical detent spring 48 retains the valve piston in right hand position While the motor is moving, so that the operator can release the handle l5 immediately after shifting it, and the valve piston will automatically return to neutral when the motor piston Illa has completed its movement to the right. Thus, as shown in Fig. 4, when the piston |0a bottoms against the right end of the motor cylinder, fluid flow is stopped, and the pressure immediately rises in th inlet port 25 and the valve piston passage 32 to the predetermined value which is suflicient to overcome the spring 39 and open the relief valve 34 to discharge fluid through radial ports 65 into a body passage 66 leading back to the return port 26. The opening movement of this valve carries the connected sleeve to the right, closing the gap between it and the sleeve 4|, and in doing so, displaces the annular detent spring 48 out of the gap. Since, thereafter, the detent spring 48 simply bears against the smooth cylindrical surfaceformed by the abutting sleeves 36 and 4|, it is unable to retain the valve piston in righthand position and the latter is moved back to the neutral position shown in Fig. 2 by the centering spring 50. This movement of the valve piston reconnects the pressure port 25 directly to the return port 23, releasing the pressure of the fluid, whereupon the relief valve 34 closes, and the corresponding movement of the sleeve 36 away from the sleeve 4| restores the gap 45.

When the valve piston 24 is moved to the left, as shown in Fig. 5, it is retained in actuated position by a second annular detent spring 62 positioned in a second annular groove 63 in the valve body 22, which spring is then juxtapositioned to the gap between the sleeves 36 and 4|. When the motor piston Ilia has completed its movement and bottoms in the left end of the motor cylinder, the pressure in the valve passage 32 again rises to the predetermined high value necessary to open the relief valve 34, and the opening of the valve again moves the sleeve 35 into contact with the sleeve 4|, eliminating the gap between the sleeves so that the detent spring 32 is disabled as to its holding function, and the centering spring again restores the valve piston to neutral position.

To insure that the relief valve 34 will open a sufiicient distance to close the gap 45 between the sleeves 35 and 4|, the bor 32a at the right end of the passage 32 is extended beyond the radial ports 65, the valve 34 sealing with the bore 32a, so that no appreciable fluid can be discharged to relieve the pressure until the valve 34 has opened sufficiently to close the gap 45.

It is to be noted that during movement of the motor piston Illa, the pressure fluid is applied through fully opened channels in the valve to the motor cylinder so that there is no appreciable pressure drop, and the full pump pressure is effective against the motor piston. Likewise, the exhaust passages through the valve connecting the other end of the motor cylinder to the return port 26 are fully opened so that there is no back pressure. This feature is not found in prior known self-holding valves in which a pressure drop produced by flow of fluid through the valve is utilized to hold the valve in open position until the motor has completed its stroke.

Summarizing, the present invention resides in the combination with a pair of inner and outer telescoping members (constituted by the sleeve 24c and the body 22) of a detent mechanism for releasably retaining the members in a predetermined relative position, which detent mechanism comprises:

(1) A pair of coaxial cylindrical elements (constituted by the sleeve 33 and the sleeve 4|) of the same external diameter on the member 24c and movable as a unit therewith, and also relatively movable apart from each other to form a recess 45 therebetween and movable together into abutting relation to eliminate the recess;

(2) A spring detent (the annular spring 62 or 43) on the other member 22 movable therewith past the one member Me and engageable with the recess when the elements 36 and 4| are apart and the members are in said predetermined position; and

(3) Means (the pressure-actuated valve 34) for moving the elements 36 and 4| together to eliminate the recess 45 and thereby eject the detent (spring 62 or spring 48) therefrom, to reduce the retaining effect of the detent mechanism on the members.

Although for the purpose of explainin the invention, a particular embodiment thereof has been shown and described, obvious modifications will occur to a person skilled in the art, and I do not desire to be limited to the exact details shown and described.

I claim:

In combination with a pair of inner and outer telescoping members relatively movable past each other, a detent mechanism for releasably retaining said members in a predetermined relative position comprising: a pair of coaxial cylindrical elements of the same external diameter on one of said members movable as a unit therewith and relatively movable apart from each other to form a recess therebetween and together into abutting relation to eliminate said recess; a spring detent on said other member movable therewith past said One member and engageable with said recess when said elements are apart and said members are in said predetermined position; and means for moving said elements together to eliminate said recess and thereby eject said detent therefrom, to reduce the retaining effect of said detent mechanism on said members.

CARLOS B. LIV'ERS.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,932,736 Janette Oct. 31, 1933 1,935,715 Hunt et a1 Nov. 21, 1933 1,983,063 Baits Dec. 4, 1934 2,643,434 Hagedorn June 9, 1936 2,044,492 Baldwin June 16, 1936 2,439,116 Waterman Apr. 6, 1948 2,446,355 Wright Aug. 3, 1948 

